Urinary β2-Microglobulin is a Sensitive Indicator for Renal Tubular Injury

After filtration through the glomeruli of the kidney, β2-microglobulin is reabsorbed by the renal proximal tubules. Increase in urinary β2-microglobulin indicates tubular dysfunction, and measurement of β2-microglobulin in urine sediment is useful to determine the source of kidney injury. CD133 has recently been characterized as a progenitor cell marker in the kidney, detecting injured epithelial cells in the proximal tubules. This study was designed to evaluate the correlation of increase in urinary β2-microglobulin and CD133 staining in patients with tubular injury. Methods: Between 2009 and 2012, 47 patients with renal biopsies had prior RenalVysion ™ analysis. Among these, 30 patients had elevated urinary β2-microglobulin, the remaining 17 had normal range of urinary β2-microglobulin. Immunohistochemical staining for CD133 was performed in the corresponding renal biopsy specimens. Confluent CD133 staining in proximal tubules was considered positive. The correlation of urinary β2-microglobulin and CD13